As shown in FIG. 1, in a conventional DC-to-DC converter 10 to convert an input voltage VIN to an output voltage VOUT, two Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) 12 and 14 are employed for the high-side and low-side power switches in a power stage to be alternatively switched by control signals UG and LG provided by a controller 16 to regulate a current I flowing through an inductor L to charge a capacitor C to produce the output voltage VOUT. When integrated circuit scaled down, MOSFET will have too large conductive resistance to satisfy the designers' requirements and therefore, it is intended for other element having lower conductive resistance for the power switches for less power loss within the switches. Junction Field-Effect Transistor (JFET) is potential candidate as semiconductor switch with lower conductive resistance and lower cost. In U.S. Pat. Nos. 6,580,252 and 6,356,059 to Yu, normally-off enhancement mode JFET is used for the power switches of boost converter and buck converter to reduce the voltage drop loss at ON-state and the state transition time. However, these arts are still not perfect enough. On the other hand, the MOSFETs 12 and 14 of the converter 10 are required to be individually formed in two chips for the heat dissipation issue and therefore, bonding wire of package is needed for the electrically connection between the MOSFETs 12 and 14, thereby causing parasitic inductance and resistance to degrade the switching performance and efficiency.
Therefore, it is desired an electronic device with lower conductive resistance than that of MOSFET and without bonding wire of package between switches.